The screen dimmed slightly as the next module loaded.
The cursor blinked again.
_
Pran leaned forward.
The robot was standing beside the message panel again.
[^_^]
/| |\
/ \
A new system message appeared.
PYTHON MODULE PROGRESS: 60%
NEXT MODULE: DATA STORAGE
Pran nodded.
"Data storage… that sounds familiar."
He had already learned something like this in C.
Back then, the computer used arrays to store multiple values.
The system displayed another message.
PYTHON USES LISTS
Pran tilted his head.
"Lists?"
The computer showed an example.
numbers = [10, 20, 30, 40]
Pran read it slowly.
Inside the square brackets were multiple numbers.
That meant the variable numbers could hold several values at once.
The robot explained.
A LIST STORES MULTIPLE VALUES IN ONE VARIABLE
Pran typed the program into the editor.
numbers = [10, 20, 30, 40]
print(numbers)
He ran it.
The output appeared.
[10, 20, 30, 40]
Pran smiled.
"So the computer stored all four numbers."
But what if he wanted to see only one value?
The computer showed the next example.
numbers = [10, 20, 30, 40]
print(numbers[0])
Pran ran the program again.
The output appeared.
10
He nodded.
"That looks like arrays in C."
Exactly.
Just like arrays, lists also use indexes.
Indexes tell the computer which position to access.
The robot displayed a diagram.
Index: 0 1 2 3
Value: 10 20 30 40
So:
numbers[0] → 10
numbers[1] → 20
numbers[2] → 30
numbers[3] → 40
Pran experimented.
He changed the program.
numbers = [10, 20, 30, 40]
print(numbers[2])
He ran it.
The screen printed:
30
Pran smiled.
"Easy enough."
But lists can also store different kinds of values.
The computer showed another example.
items = ["apple", "banana", "orange"]
print(items[1])
Pran ran it.
The output appeared.
banana
The robot nodded proudly.
LIST STORAGE VERIFIED
Pran leaned back in the chair.
"So lists can store numbers… or text."
Exactly.
Lists are used everywhere in programming.
For example:
storing player scores in a game
storing items in a shopping cart
storing sensor data in a program
storing names in a list
The computer screen flickered again.
Another message appeared.
LIST MODIFICATION TEST
Pran looked curious.
"Modification?"
The system showed another example.
numbers = [10, 20, 30, 40]
numbers[1] = 50
print(numbers)
Pran ran the program.
The output appeared.
[10, 50, 30, 40]
Pran nodded.
"So we can change values too."
Lists are very flexible.
You can:
read values
change values
add new values
remove values
The robot jumped happily.
[^O^]
/| |\
/ \
Another message appeared.
DATA STORAGE MODULE VERIFIED
Then another.
PYTHON MODULE PROGRESS: 70%
Pran crossed his arms.
"Seventy percent already."
The computer displayed another system message.
NEXT MODULE: TOOL CREATION
Pran raised an eyebrow.
"Tool creation?"
The robot displayed another word.
FUNCTIONS
Pran smiled.
He remembered functions from the C section.
Functions allow programmers to create their own reusable commands.
The cursor blinked again.
_
Waiting.
Ready for the next lesson.
Pran placed his hands on the keyboard again.
"Alright," he said.
"Let's start building tools."
Next Chapter
Chapter 18 — Building Functions
You will learn:
Python functions
creating reusable code
parameters and return values